The present invention relates to test sockets for semiconductor devices, such as ball grid array semiconductor packages, chip scale semiconductor packages, integrated circuit devices, etc. More particularly, the present invention relates to a test socket including an interchangeable guide plate that may be removed without substantial maintenance actions.
With reference to FIG. 1, a side view of a conventional test socket 10 is shown. The test socket 10 is used to receive successive semiconductor devices 12 in order to perform various quality assurance tests, such as electrical performance tests. The semiconductor devices 12 typically include a plurality of electrical terminals 14 that are electrically connected to operative circuitry of the device. In end use, the electrical terminals 14 of the semiconductor devices 12 are soldered to corresponding terminals (or pads) of a printed circuit board in order to access the functionality of the operative circuitry. The soldering process, however, permanently deforms the electrical terminals 14 of the semiconductor devices 12 and, therefore, is an unsuitable process for use during quality assurance testing. Further, the soldering process is not suitable when bare semiconductor chips (or dice) are subject to quality assurance tests.
The test socket 10 is capable of releasably receiving the semiconductor devices 12 and biasing the electrical terminals 14 thereof against corresponding terminals of a printed circuit board 20 without significant permanent deformation of the electrical terminals 14. Thus, quality assurance tests may be performed on a given semiconductor device 12 while in the test socket 10 and the semiconductor device 12 may be subsequently removed without suffering significant deformation.
With further reference to FIG. 2, which shows the test socket 10 decoupled from the printed circuit board 20, the test socket 10 includes a guide plate 16 that engages the semiconductor device 12 and maintains the electrical terminals 14 of the semiconductor device 12 in registration with the corresponding electrical terminals of the printed circuit board 20. In particular, the guide plate 16 includes a support structure 18 that engages a periphery of the semiconductor device 12 in order to maintain the semiconductor 12 in registration with the electrical terminals of the printed circuit board 20. The dimensions of the support structure 18 are matched with the dimensions of the semiconductor device 12. Therefore, when different sizes of semiconductor devices 12 are to be tested (as is common when non-standardized chip scale semiconductor packages are tested), the guide plate 16 must be changed. As best seen in FIG. 2, this entails decoupling the test socket 10 from the printed circuit board 20. Indeed, the guide plate 16 is maintained in registration with the electrical terminals of the printed circuit board 20 by way of a peripheral flange 22 of the guide plate 16 and a corresponding undercut 24 of the test socket 10. When the test socket 10 is coupled to the printed circuit board 20 (usually by way of machine screws, not shown) the undercut 24 biases the peripheral flange 22 of the guide plate 16 against the printed circuit board 20.
The electrical terminals 14 of the semiconductor device 12 are biased against the corresponding electrical terminals of the printed circuit board 20 by way of latches 15 (or levers) that may releasably engage the semiconductor device 12.
Unfortunately, the removal of the test socket 10 from the printed circuit board 20 involves a significant effort, as a technician must remove several machine screws, lift the test socket 10, exchange the guide plate 16, and then reassemble the components. This problem is exacerbated when the quality assurance process involves the use of hundreds of such test sockets 10 and a change in the dimensions of the semiconductor device 12 requires maintenance actions on hundreds of assemblies. These maintenance actions result in a loss of time and coinciding increase in costs associated with the quality assurance testing process.
Accordingly, there is a need in the art for a new test socket that is capable of receiving different sized semiconductor devices without requiring removal from an associated PC board or other substantial maintenance actions.
A test socket for a semiconductor device, includes: a guide plate operable to receive the semiconductor device and to maintain electrical terminals of the semiconductor device in registration with electrical terminals of a base; a shell operable to couple to the base and to maintain the guide plate in registration with the electrical terminals of the base, the shell including an aperture in communication with the base through which the guide plate can be inserted and removed when the shell is coupled to the base; and at least one fastener coupled to the shell and operable to maintain the semiconductor device in engagement with the guide plate and to urge the electrical terminals of the semiconductor device in contact with the electrical terminals of the base. Preferably, the base is a printed circuit board.
The guide plate may include a periphery, and the aperture may be transversely directed through the shell with respect to the base and include one or more inside surfaces that operatively engage the periphery of the guide plate to prevent substantial lateral movement of the guide plate with respect to the base but permit sliding egress of the guide plate away from the base and through the aperture.
Preferably, the at least one fastener is movable between at least first and second positions, the first position causing the at least one fastener to maintain the semiconductor device in engagement with the guide plate and to urge the electrical terminals of the semiconductor device in contact with the electrical terminals of the base, and the second position permitting removal of the semiconductor device from the test socket and egress of the guide plate from the aperture of the shell.
The test socket preferably further includes at least one stop member coupled to the guide plate and operable to engage the at least one fastener, when in the first position, such that the guide plate is maintained in the aperture of the shell. The at least one stop member may be formed from a compressible material such that the guide plate is resiliently urged toward the base when the at least one fastener is moved into the first position.
Preferably, the at least one fastener includes one or more levers, each including a proximal end hingedly coupled to the shell and a distal end such that the lever is rotatable between at least first and second positions, the first position causing the distal end of the lever to maintain the semiconductor device in engagement with the guide plate and to urge the electrical terminals of the semiconductor device in contact with the electrical terminals of the base, and the second position permitting removal of the semiconductor device from the test socket and egress of the guide plate from the aperture of the shell. The respective distal ends of the one or more levers may be operable to engage the semiconductor device and the at least one stop member of the guide plate when the one or more levers are in the first position. The respective one or more levers may be operable to engage the at least one stop member of the guide plate at an intermediate position between the proximal and distal ends thereof.
In accordance with one or more further aspects of the present invention, a method for using a test socket for a semiconductor device is disclosed. The test socket may comprise a shell coupled to a base, the shell having an aperture and being operable to maintain a guide plate in registration with electrical terminals of the base, the method comprising: inserting a guide plate into the aperture of the shell without decoupling the shell from the base, the guide plate being operable to maintain electrical terminals of the semiconductor device in registration with the electrical terminals of the base; inserting the semiconductor device into the guide plate; and actuating at least one fastener such that the semiconductor device is maintained in engagement with the guide plate and the electrical terminals of the semiconductor device are urged in contact with the electrical terminals of the base.
Preferably, the method further includes: deactivating the at least one fastener such that the semiconductor device may be removed from the guide plate; and extracting the guide plate from the aperture of the shell without decoupling the shell from the base.
Other aspects, features, and advantages of the invention will be apparent from the disclosure herein taken in conjunction with the accompanying drawings.